Many facility installations use an automatic transfer switch (ATS) to maintain power and protect against power outages. Certain installations, e.g., data centers, hospitals, water treatment plants and the like, need power systems (hereinafter “the system load”) structured to provide a substantially uninterruptible power supply. In these cases, redundant power sources are desired. The primary power source is usually the public power grid and the secondary power source is usually a generator. However, the power sources can be different utility grids or even all generators or other power sources. For example, an Uninterruptible Power Supply (UPS) can be a power source for a small amount of time. Basically any power source that need to be switched with a load output can be a power source.
The ATS switches are used to protect critical electrical loads against loss of power. The load's primary of first power source is backed up by a second power source. The transfer switch is connected to both of the power sources and supplies the load with power from one of the sources. In the event that power is lost from the first power source, the transfer switch transfers the load to the second power source. This transfer is automatic.
The ATS assembly can include a Bypass (Isolation) switch. The Bypass switch is an assembly used with a transfer switch that electrically isolates the transfer switch for inspection and/or maintenance. The ATS with Bypass switch assembly typically has two separate switches or switch (sub) assemblies, the ATS switch and the Bypass switch, that can transfer power to the system load. Each of the two switches has positions to transfer the load from a primary power source (e.g., S1) to a back-up power source (e.g., S2). The ATS switch is the main switch that transfers power and the Bypass switch is typically used for when the ATS switch is in maintenance. The Bypass switch has an assembly that is usually fixed within the enclosure although there is a removable Bypass switch assembly that can be slidably withdrawn on rails. The main difference is that the fixed configuration Bypass switch does not have a truck or rail to slidably allow the device to be drawn out in contrast to a removable type. See, e.g., U.S. Pat. No. 7,973,253, and U.S. Patent Application Publication No. 2010/0141047, the contents of which are hereby incorporated by reference as if recited in full herein.
Despite the above, there remains a need for alternate ATS assembly configurations.